The invention relates to a water-saving aerating shower head which is adjustable to obtain a range of shower patterns differing in water density or "wetness" to limit water output to a minimum having regard to the need for more water for effective rinsing following soaping or the application of shampoo to the hair. While the actual amount of water flowing to and through the shower head remains constant, it has been found that the minimum concentration of water in an aerated shower pattern sufficient for wetting the skin and hair for soaping and washing purposes is inadequate for satisfactory rinsing and that this deficiency of known aerating shower heads can be rectified by narrowing the flow pattern to concentrate the water content and bring to bear adequate rinse water at locations where rinsing has not yet been completed.
A wide variety of shower heads have heretofore been devised and used, ranging from simple sprinkling can type which provides a cluster of small streams of water to complicated and frequently adjustable heads which supply a wide range of shower patterns. While conservation of water, especially hot water, has been an objective in the designing of some of these shower heads, energy shortages and greatly increasing cost of gas, oil and electricity have emphasized the need and wisdom of hot water conservation. Aeration of the water as it is emitted by the shower head nozzle has been a step in the direction of conservation. True and effective aeration requires the aspiration of air at the outlet of the nozzle aperture or orifices although some aeration takes place even in the shower patterns of heads not specifically designed for aeration. Shower heads similar to that of the present invention but lacking any means of adjustment to vary the characteristics of the emitted shower pattern are known. Such heads comprise a body having a more or less conical or flaring outlet passageway extending downstream from a transverse nozzle plate of thin metal having a circular cluster of small orifices through which the water flows in as many jets into the outlet passageway. To some extent, air is aspirated by the several jet streams into at least the downstream portion of the outlet passageway to break up the individual jet streams and effect a degree of atomization. This break-up action is continued to some extent as the water emerges from the shower head. The result is a shower pattern having a fixed rate of flare and water concentration characteristics.
It has been found that the flare pattern of a shower head of this type is determined at least partly by the length of the outlet passageway downstream from the nozzle plate of the shower head. For a given supply water pressure, thickness and orifice pattern of the nozzle plate and rate of flare of the outlet passageway of the shower head, the rate of flare and water concentration of the shower pattern is determined by the length of the outlet passageway downstream from the nozzle plate. It has been found that, within limits, the greater this distance, the smaller the rate of flare of the shower pattern and the greater the concentration of the air-borne atomized water emitted for showering purposes and, per contra, the shorter this distance the greater the rate of flare and therefore area of coverage albeit with lower concentration of water in the shower pattern.
The object of the present invention is to provide a water-saving, aerating shower head which can be adjusted by the user while taking a shower to emit a shower pattern within a range of rates of flare from large with low concentration of atomized water to small, more focused pattern containing a relatively high concentration of water. A further object is to provide such a shower head with a sharp-edged passageway outlet which emits a sharply defined shower pattern of air-borne atomized water with a formation of drops of water which drip to the floor.
A subservient object is to provide an adjusting mechanism which rotates to a limited extent the body of the shower head with respect to the fixed nozzle plate in the course of effecting the desired adjustment to effect the self-cleaning of the narrow space between the nozzle plate assembly and the inside surface of the outlet passageway upstream extended.
In summary, the invention contemplates an aerating shower head comprising a body having a substantially cylindrical passageway therethrough which terminates at its outlet end in a sharp edge and contains within the inlet end of the passageway an axially movable sleeve including the transverse nozzle plate, the axial position of the sleeve being determined by an eccentric mechanism including an externally rotatable portion having an eccentric pin engaging the sleeve.